diff --git a/include/sqlpp11/core/aggregate_function/avg.h b/include/sqlpp11/core/aggregate_function/avg.h
index 69f9a805..1b6336d8 100644
--- a/include/sqlpp11/core/aggregate_function/avg.h
+++ b/include/sqlpp11/core/aggregate_function/avg.h
@@ -48,7 +48,6 @@ namespace sqlpp
     using _traits = make_traits<integral, tag::is_expression /*, tag::is_selectable*/>;
 
     using _can_be_null = std::false_type;
-    using _is_aggregate_expression = std::true_type;
 
     constexpr avg_t(Expr expr) : _expr(std::move(expr))
     {
@@ -64,7 +63,7 @@ namespace sqlpp
   };
 
   template <typename Flag, typename Expr>
-  struct is_aggregate<avg_t<Flag, Expr>> : public std::true_type
+  struct contains_aggregate<avg_t<Flag, Expr>> : public std::true_type
   {
   };
 
diff --git a/include/sqlpp11/core/aggregate_function/count.h b/include/sqlpp11/core/aggregate_function/count.h
index 03550926..bffbf802 100644
--- a/include/sqlpp11/core/aggregate_function/count.h
+++ b/include/sqlpp11/core/aggregate_function/count.h
@@ -48,7 +48,6 @@ namespace sqlpp
     using _traits = make_traits<integral, tag::is_expression /*, tag::is_selectable*/>;
 
     using _can_be_null = std::false_type;
-    using _is_aggregate_expression = std::true_type;
 
     constexpr count_t(Expr expr) : _expr(std::move(expr))
     {
@@ -64,7 +63,7 @@ namespace sqlpp
   };
 
   template <typename Flag, typename Expr>
-  struct is_aggregate<count_t<Flag, Expr>> : public std::true_type
+  struct contains_aggregate<count_t<Flag, Expr>> : public std::true_type
   {
   };
 
diff --git a/include/sqlpp11/core/aggregate_function/max.h b/include/sqlpp11/core/aggregate_function/max.h
index 008792ae..2cd5ad8a 100644
--- a/include/sqlpp11/core/aggregate_function/max.h
+++ b/include/sqlpp11/core/aggregate_function/max.h
@@ -47,7 +47,6 @@ namespace sqlpp
   {
     using _traits = make_traits<value_type_of_t<Expr>, tag::is_expression, tag::is_selectable>;
     using _can_be_null = std::true_type;
-    using _is_aggregate_expression = std::true_type;
 
     constexpr max_t(Expr expr) : _expr(std::move(expr))
     {
@@ -63,7 +62,7 @@ namespace sqlpp
   };
 
   template <typename Flag, typename Expr>
-  struct is_aggregate<max_t<Flag, Expr>> : public std::true_type
+  struct contains_aggregate<max_t<Flag, Expr>> : public std::true_type
   {
   };
 
diff --git a/include/sqlpp11/core/aggregate_function/min.h b/include/sqlpp11/core/aggregate_function/min.h
index 78b78ee1..42b36032 100644
--- a/include/sqlpp11/core/aggregate_function/min.h
+++ b/include/sqlpp11/core/aggregate_function/min.h
@@ -47,7 +47,6 @@ namespace sqlpp
   {
     using _traits = make_traits<value_type_of_t<Expr>, tag::is_expression, tag::is_selectable>;
     using _can_be_null = std::true_type;
-    using _is_aggregate_expression = std::true_type;
 
     constexpr min_t(Expr expr) : _expr(std::move(expr))
     {
@@ -63,7 +62,7 @@ namespace sqlpp
   };
 
   template <typename Flag, typename Expr>
-  struct is_aggregate<min_t<Flag, Expr>> : public std::true_type
+  struct contains_aggregate<min_t<Flag, Expr>> : public std::true_type
   {
   };
 
diff --git a/include/sqlpp11/core/aggregate_function/over.h b/include/sqlpp11/core/aggregate_function/over.h
index 776f621a..0441cfd6 100644
--- a/include/sqlpp11/core/aggregate_function/over.h
+++ b/include/sqlpp11/core/aggregate_function/over.h
@@ -50,11 +50,6 @@ namespace sqlpp
     Expr _expr;
   };
 
-  template <typename Expr>
-  struct is_aggregate<over_t<Expr>> : public is_aggregate<Expr>
-  {
-  };
-
   template<typename Expr>
   struct name_tag_of<over_t<Expr>> : public name_tag_of<Expr> {};
 
@@ -67,7 +62,7 @@ namespace sqlpp
   struct value_type_of<over_t<Expr>>: public value_type_of<Expr> {};
 
   template<typename Expr>
-  using check_over_args = ::sqlpp::enable_if_t<is_aggregate<Expr>::value>;
+  using check_over_args = ::sqlpp::enable_if_t<contains_aggregate<Expr>::value>;
 
   template <typename Context, typename Expr>
   auto to_sql_string(Context& context, const over_t<Expr>& t) -> std::string
diff --git a/include/sqlpp11/core/aggregate_function/sum.h b/include/sqlpp11/core/aggregate_function/sum.h
index 5d4eac34..b3fe1122 100644
--- a/include/sqlpp11/core/aggregate_function/sum.h
+++ b/include/sqlpp11/core/aggregate_function/sum.h
@@ -47,7 +47,6 @@ namespace sqlpp
   {
     using _traits = make_traits<value_type_of_t<Expr>, tag::is_expression, tag::is_selectable>;
     using _can_be_null = std::true_type;
-    using _is_aggregate_expression = std::true_type;
 
     constexpr sum_t(Expr expr) : _expr(std::move(expr))
     {
@@ -63,7 +62,7 @@ namespace sqlpp
   };
 
   template <typename Flag, typename Expr>
-  struct is_aggregate<sum_t<Flag, Expr>> : public std::true_type
+  struct contains_aggregate<sum_t<Flag, Expr>> : public std::true_type
   {
   };
 
diff --git a/include/sqlpp11/core/type_traits.h b/include/sqlpp11/core/type_traits.h
index e0e0db41..1f8eae67 100644
--- a/include/sqlpp11/core/type_traits.h
+++ b/include/sqlpp11/core/type_traits.h
@@ -43,6 +43,8 @@
 #include <sqlpp11/core/detail/type_vector.h>
 #include <sqlpp11/core/detail/type_set.h>
 #include <sqlpp11/core/detail/get_first.h>
+#include <sqlpp11/core/type_traits/aggregates.h>
+#include <sqlpp11/core/type_traits/nodes_of.h>
 
 namespace sqlpp
 {
@@ -126,7 +128,6 @@ namespace sqlpp
   template <typename T>
   using value_type_of_t = typename value_type_of<T>::type;
 
-#warning: Add partial specialization to handle const?
   template<typename T>
   struct value_type_of<::sqlpp::optional<T>>
   {
@@ -505,13 +506,6 @@ namespace sqlpp
   using is_database =
       typename std::conditional<std::is_same<Database, void>::value, std::false_type, std::true_type>::type;
 
-  template <typename T>
-  struct nodes_of {
-    using type = detail::type_vector<>;
-  };
-  template <typename T>
-  using nodes_of_t = typename nodes_of<T>::type;
-
 #define SQLPP_RECURSIVE_TRAIT_SET_GENERATOR(trait)                                      \
   namespace detail                                                                      \
   {                                                                                     \
@@ -585,13 +579,6 @@ namespace sqlpp
         ;
   };
 
-  template<typename T>
-    struct is_aggregate : public std::false_type{};
-
-#warning: Need to make this recursive! and then add tests!
-  template<typename T>
-    struct contains_aggregate : public std::false_type{};
-
   namespace detail
   {
     template <typename KnownAggregates, typename T, typename Leaf = void>
diff --git a/include/sqlpp11/core/type_traits/aggregates.h b/include/sqlpp11/core/type_traits/aggregates.h
new file mode 100644
index 00000000..0fae846e
--- /dev/null
+++ b/include/sqlpp11/core/type_traits/aggregates.h
@@ -0,0 +1,47 @@
+#pragma once
+
+/*
+ * Copyright (c) 2024, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice, this
+ *   list of conditions and the following disclaimer in the documentation and/or
+ *   other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sqlpp11/core/detail/type_vector.h>
+#include <sqlpp11/core/type_traits/nodes_of.h>
+#include <sqlpp11/core/logic.h>
+
+namespace sqlpp
+{
+  template <typename T>
+  struct contains_aggregate : public std::integral_constant<bool, contains_aggregate<nodes_of_t<T>>::value>
+  {
+  };
+
+  template <typename... T>
+  struct contains_aggregate<detail::type_vector<T...>>
+      : public std::integral_constant<bool, logic::any_t<contains_aggregate<T>::value...>::value>
+  {
+  };
+
+}  // namespace sqlpp11
+
diff --git a/include/sqlpp11/core/type_traits/nodes_of.h b/include/sqlpp11/core/type_traits/nodes_of.h
new file mode 100644
index 00000000..321a8494
--- /dev/null
+++ b/include/sqlpp11/core/type_traits/nodes_of.h
@@ -0,0 +1,43 @@
+#pragma once
+
+/*
+ * Copyright (c) 2024, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice, this
+ *   list of conditions and the following disclaimer in the documentation and/or
+ *   other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sqlpp11/core/detail/type_vector.h>
+
+namespace sqlpp
+{
+
+  template <typename T>
+  struct nodes_of
+  {
+    using type = detail::type_vector<>;
+  };
+  template <typename T>
+  using nodes_of_t = typename nodes_of<T>::type;
+
+}  // namespace sqlpp11
+
diff --git a/tests/core/types/CMakeLists.txt b/tests/core/types/CMakeLists.txt
index 58a24dbd..37771630 100644
--- a/tests/core/types/CMakeLists.txt
+++ b/tests/core/types/CMakeLists.txt
@@ -37,3 +37,4 @@ test_compile(value)
 
 add_subdirectory(aggregate_function)
 add_subdirectory(operator)
+add_subdirectory(type_traits)
diff --git a/tests/core/types/type_traits/CMakeLists.txt b/tests/core/types/type_traits/CMakeLists.txt
new file mode 100644
index 00000000..2786010e
--- /dev/null
+++ b/tests/core/types/type_traits/CMakeLists.txt
@@ -0,0 +1,32 @@
+# Copyright (c) 2024, Roland Bock
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without modification,
+# are permitted provided that the following conditions are met:
+#
+#   Redistributions of source code must retain the above copyright notice, this
+#   list of conditions and the following disclaimer.
+#
+#   Redistributions in binary form must reproduce the above copyright notice, this
+#   list of conditions and the following disclaimer in the documentation and/or
+#   other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+function(test_compile name)
+    set(target sqlpp11_core_types_operator_${name})
+    add_executable(${target} ${name}.cpp)
+    target_link_libraries(${target} PRIVATE sqlpp11::sqlpp11 sqlpp11_testing)
+endfunction()
+
+test_compile(aggregates)
+
diff --git a/tests/core/types/type_traits/aggregates.cpp b/tests/core/types/type_traits/aggregates.cpp
new file mode 100644
index 00000000..376cad8c
--- /dev/null
+++ b/tests/core/types/type_traits/aggregates.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2024, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "MockDb.h"
+#include "Sample.h"
+#include <sqlpp11/sqlpp11.h>
+
+namespace
+{
+  auto db = MockDb{};
+
+  template <typename T, typename V>
+  using is_same_type = std::is_same<sqlpp::value_type_of_t<T>, V>;
+}
+
+template <typename Value>
+void test_aggregates(Value v)
+{
+  auto v_not_null = sqlpp::value(v);
+  auto v_maybe_null = sqlpp::value(::sqlpp::make_optional(v));
+
+  using OptFloat = sqlpp::value_type_of_t<::sqlpp::optional<float>>;
+
+#warning: Need to test contains_aggregate
+
+}
+
+int main()
+{
+  // boolean
+  test_avg(bool{true});
+
+  // integral
+  test_avg(int8_t{7});
+  test_avg(int16_t{7});
+  test_avg(int32_t{7});
+  test_avg(int64_t{7});
+
+  // unsigned integral
+  test_avg(uint8_t{7});
+  test_avg(uint16_t{7});
+  test_avg(uint32_t{7});
+  test_avg(uint64_t{7});
+
+  // floating point
+  test_avg(float{7.7});
+  test_avg(double{7.7});
+
+#warning: Should there be avg date time duration?
+#if 0
+  // date
+  test_avg(::sqlpp::chrono::day_point{});
+
+  // timestamp
+  test_avg(::sqlpp::chrono::microsecond_point{});
+  using minute_point = std::chrono::time_point<std::chrono::system_clock, std::chrono::minutes>;
+  test_avg(minute_point{});
+
+  // time_of_day
+  test_avg(std::chrono::microseconds{});
+#endif
+}
+